Accessing Parameter Values

This section provides an introduction to functions that enable you to access parameter values.

C8Float C8GetFloat(C8Udf *ctx, C8UInt ndx) – Purpose: Provides the floating point value of a parameter.
Parameters:
- ctx: A context object that contains information about the parameters passed to the UDF.
- nd: Indicates which parameter in the context object to get the value of. The first parameter is parameter 0.
Returns: The floating point value of the specified parameter.
C8Int C8GetInt(C8Udf *ctx, C8UInt ndx) – Purpose: Provides the integer value of a parameter.
Parameters:
- ctx: A context object that contains information about the parameters passed to the UDF.
- ndx: Indicates which parameter in the context object to get the value of. The first parameter is parameter 0.
Returns: The integer value of the specified parameter.
C8Long C8GetLong(C8Udf *ctx, C8UInt ndx) – Purpose: Provides the long value of a parameter.
Parameters:
- ctx: A context object that contains information about the parameters passed to the UDF.
- ndx: Indicates which parameter in the context object to get the value of. The first parameter is parameter 0.
Returns: The long value of a parameter.
const C8Char *C8GetCharPtr(C8Udf *ctx, C8UInt ndx) – Purpose: Provides the C8Char pointer value of a parameter.
Parameters:
- ctx: A context object that contains information about the parameters passed to the UDF.
- ndx: Indicates which parameter in the context object to get the value of. The first parameter is parameter 0.
Returns: The C8Char pointer value of the specified parameter. C8Char pointer corresponds to the CCL "STRING" data type. The return value of this accessor function is a pointer to a normal C string (a sequence of ASCII characters terminated with a 0 ('\0'). Note that the server (not the UDF) allocated the memory for this string, and therefore the server (not the UDF) is responsible for freeing the memory for this string. Do not modify or free this string, or change the value of the C8Char pointer (for example, to point to something else).
C8Timestamp C8GetTimestamp(C8Udf *ctx, C8UInt ndx) – Purpose: Provides the timestamp value of a parameter. timestamps are in microsecond units.
Parameters:
- ctx: A context object that contains information about the parameters passed to the UDF.
- ndx: Indicates which parameter in the context object to get the value of. The first parameter is parameter 0.
Returns: The timestamp value of the specified parameter. Sybase CEP timestamps are in microsecond units.
C8Interval C8GetInterval(C8Udf *ctx, C8UInt ndx) – Purpose: Provides the interval value of a parameter. intervals are in microsecond units.
Parameters:
- ctx: A context object that contains information about the parameters passed to the UDF.
- ndx: Indicates which parameter in the context object to get the value of. The first parameter is parameter 0.
Returns: The interval value of a parameter. Sybase CEP intervals are in microsecond units.
C8Bool C8GetBool(C8Udf *ctx, C8UInt ndx) – Purpose: Provides the boolean value of a parameter.
Parameters:
- ctx: A context object that contains information about the parameters passed to the UDF.
- ndx: Indicates which parameter in the context object to get the value of. The first parameter is parameter 0.
Returns: The boolean value of a parameter. Valid C8Boolean values (C8_TRUE and C8_FALSE) are defined in the c8udf.h file.
C8Bool C8GetIsNull(C8Udf *ctx, C8UInt ndx) – Purpose: Return the NULL status for the parameter. A return value of C8_FALSE means a non-NULL value is being passed, and a value of C8_TRUE means a NULL is being passed. If a NULL is passed, the parameter value is undefined.
Parameters:
- ctx: A context object that contains information about the parameters passed to the UDF.
- ndx: Indicates which parameter in the context object to get the value of. The first parameter is parameter 0.
Returns: C8_TRUE if a NULL is being passed; C8_FALSE if a non-NULL value is being passed.
const C8Blob *C8GetBlob(C8Udf *ctx, C8UInt ndx) – Purpose: Returns a pointer to the BLOB value of a parameter. If the BLOB is NULL, the function returns 0. If the BLOB is empty, the function returns a non-zero pointer.
Parameters:
- ctx: A context object that contains information about the parameters passed to the UDF.
- ndx: Indicates which parameter in the context object to get the value of. The first parameter is parameter 0.
Returns: A pointer to a BLOB. The value is a "raw" BLOB (as opposed to a hex string or a base64 string). For an explanation of raw vs. hex string vs. base64 string formats, see Data Types and Subroutines for UDFs and In-process Adapters.

The return value is a pointer. Do not change the memory that the pointer points to, or C8Free() this pointer.
C8Char *C8GetBlobBase64String(C8Udf *ctx, C8UInt ndx) – Purpose: Returns a pointer to that parameter's BLOB value in the form of a Base64 String. If the BLOB is NULL, the function returns 0. If the BLOB is empty, the function returns a non-zero pointer.
Parameters:
- ctx: A context object that contains information about the parameters passed to the UDF.
- ndx: Indicates which parameter in the context object to get the value of. The first parameter is parameter 0.
Returns: A pointer to a BLOB in Base64 String format. For an explanation of raw vs. hex string vs. base64 string formats, see Data Types and Subroutines for UDFs and In-process Adapters.

The return value is a pointer. Do not change the memory that the pointer points to, or C8Free() this pointer.
C8UInt C8GetBlobLength(C8Udf *ctx, C8UInt ndx) – Purpose: Returns the length of the BLOB (in bytes) of a parameter. A return value of zero indicates either that the BLOB is NULL or that the length of the BLOB is zero.
To distinguish between these 2 cases (NULL vs. 0 length), you can do either of the following:
- Call C8GetIsNull()C8GetIsNull() to determine whether the BLOB is NULL.
- Check whether the pointer returned by C8GetBlob() is 0 (meaning that the BLOB is NULL) or non-zero (meaning that the BLOB is non-NULL).
Parameters:
- ctx: A context object that contains information about the parameters passed to the UDF.
- ndx: Indicates which parameter in the context object to get the value of.
Returns: The length of the BLOB. If the parameter is not of type BLOB, the server will issue an error message and the return value of the function is undefined.
C8Char *C8GetBlobHexString(C8Udf *ctx, C8UInt ndx) – Purpose: Returns a pointer to the hexadecimal representation of the BLOB value. The hexadecimal string will consist only of the characters 0 to 9 and a to f, with no line breaks or other white space. The length of the returned string is exactly 1 + 2*C8GetBlobLength() bytes including the string terminator.
Parameters:
- ctx: A context object that contains information about the parameters passed to the UDF.
- ndx: Indicates which parameter in the context object to get the value of.
Returns: A pointer to a copy of the BLOB in HexString format. For an explanation of raw vs. hex string vs. base64 string formats, see Data Types and Subroutines for UDFs and In-process Adapters.

You mustC8Free()the returned pointer or a memory leak will occur.
C8Char *C8GetAsStringXml(C8Udf *ctx, C8UInt ndx) – Purpose: Returns a pointer to a string containing the XML value.
Parameters:
- ctx: A context object that contains information about the parameters passed to the UDF.
- ndx: Indicates which parameter in the context object to get the value of. The first parameter is parameter 0.
Returns: A pointer to the XML field as a string.

You mustC8Free()the returned pointer or a memory leak will occur.

After you have evaluated the function, the user should use an output accessor function to return the value to the software. The output accessor functions are:

void C8SetOutputInt(C8Udf *ctx, C8Int value) – Purpose: Places the long value so that Sybase CEP can access the value.
Parameters:
- ctx: A context object that contains information about the parameters passed to the UDF.
- value: The value to place.
Returns: Nothing.
void C8SetOutputLong(C8Udf *ctx, C8Long value); – Purpose: Places a long value so that can access the value.
Parameters:
- ctx: A context object that contains information about the parameters passed to the UDF.
- value: The value to place.
Returns: Nothing.
void C8SetOutputFloat(C8Udf *ctx, C8Int value); – Purpose: Places the long value so that Sybase CEP can access the value.
Parameters:
- ctx: A context object that contains information about the parameters passed to the UDF.
- value: The value to place.
Returns: Nothing.
void C8SetOutputTimestamp(C8Udf *ctx, C8Timestamp value); – Purpose: Places the long value so that can access the value.
Parameters:
- ctx: A context object that contains information about the parameters passed to the UDF.
- value: The value to place.
Returns: Nothing.
void C8SetOutputInterval(C8Udf *ctx, C8Interval value); – Purpose: Places the long value so that Sybase CEP can access the value.
Parameters:
- ctx: A context object that contains information about the parameters passed to the UDF.
- value: The value to place.
Returns: Nothing.
void C8SetOutputBool(C8Udf *ctx, C8Bool value) – Purpose: Places the long value so that can access the value.
Parameters:
- ctx: A context object that contains information about the parameters passed to the UDF.
- value: The value to place.
Returns: Nothing.
void C8SetOutputCharPtr(C8Udf *ctx, C8CharPtr value) – Purpose: Places an output value so that Sybase CEP can access the value.
The second parameter of this function, C8CharPtr, is a STRING. will copy the string to its own internal buffer. You can then free or delete the string as desired. For example, your code might look like:
```
char *ErrorStr1 = NULL;
	ErrorStr1 = (char *) malloc(MaxErrorMsgSize);
	sprintf(ErrorStr1, "Error...", ...);
	C8SetOutputCharPtr(ctx, (C8CharPtr) ErrorStr1);
	free(ErrorStr1);
```
Parameters:
- ctx: A context object that contains information about the parameters passed to the UDF.
- value: The value to place.
Returns: Nothing.
void C8SetOutputBlob(C8Udf *ctx, const C8Blob *blob, const C8UInt blob_length) – Purpose: Returns the BLOB as the output value. The BLOB value must be a byte array of blob_length bytes. The BLOB is copied to an internal Sybase CEP buffe, so you should deallocate your copy after C8SetOutputBlob() returns.)
Parameters:
- ctx: A context object that contains information about the parameters passed to the UDF.
- blob: The BLOB that you want to return. The BLOB must be a raw BLOB. For an explanation of raw vs. hex string vs. base64 string formats, see Data Types and Subroutines for UDFs and In-process Adapters.
- blob_length: The length of the BLOB in bytes.
Returns: Nothing.
void C8SetOutputBlobBase64String(C8Udf *ctx, const C8Char *base64_string) – Purpose: Returns a BLOB as the output value. The BLOB is copied to an internal buffer, so you should deallocate your copy after C8SetOutputBlobBase64String() returns.)
Parameters:
- ctx: A context object that contains information about the parameters passed to the UDF.
- base64_string: The BLOB in Base64 String format that you want to return. For an explanation of raw vs. hex string vs. base64 string formats, see Data Types and Subroutines for UDFs and In-process Adapters.
Returns: Nothing.
void C8SetOutputIsNull(C8Udf *ctx) – Purpose: Sets to NULL. Any other output values are ignored if this function is used.
Parameters:
- ctx: A context object that contains information about the parameters passed to the UDF.
Returns: Nothing.